How to add RSS Feed on a blog page - twenty eleven (5 posts)

I want to add an RSS Feed on the blog page of this site http://www.finishingstrong.info and I am having difficulty. I found the widget and understand i need to use that and that part is fine. It is the url that I don't understand. How do I know what it is? Oh, and to be clear, I want people to be able to subscribe to these posts, not to pull them from someplace else.
Thanks in advance